Korean Journal of Orthodontics最新文献

Objective: Several studies have highlighted the toxic potential of bisphenol A (BPA), however, BPA release from orthopedic devices remains poorly investigated. Therefore, this study aimed to evaluate BPA levels in the saliva of children treated using Haas expanders.

Methods: Twenty-two children of both sexes aged 6-10 years who required rapid maxillary expansion were recruited. One week after placement of elastics to separate the permanent molars, orthodontic bands were adapted, and maxillary impressions were obtained using alginate impression material. Haas expanders were fabricated using a standardized amount of acrylic resin. The bands were cemented using Transbond Plus Light Cure Band (3M). Saliva samples were collected at five time points: before (T0) and 30 minutes (T1), 24 hours (T2), 1 week (T3), and 1 month (T4) after Haas expander installation. BPA levels were measured using ultra-high-performance liquid chromatography coupled with Tandem Mass Spectrometry. The results were evaluated using one-way analysis of variance with Tukey's post-hoc test (alpha = 5%).

Results: BPA levels were below the recommended tolerable daily intake (TDI) at all timepoints; however, salivary BPA levels at T1 (70.324 ng/mL ± 37.05) and at T2 (18.015 ng/mL ± 11.22) were significantly higher compared to that at T0 (0.475 ng/mL ± 0.27) (P < 0.05).

Conclusions: Salivary BPA levels significantly increased 30 minutes and 24 hours after Haas expander installation and return to baseline values after 1 week. BPA levels did not exceed the TDI, suggesting that the use of Haas expanders may be considered safe concerning BPA exposure in children.

Objective: Using finite element method (FEM) analysis of a clear aligner (CA), this study aimed to investigate the effects of varying the edentulous space on canine distal bodily movement during space closure following maxillary first premolar extraction.

Methods: FEM analysis was used to simulate distal canine bodily movement following maxillary first premolar extraction using CAs. Four CA designs for edentulous spaces were compared: no-pontic, full-pontic, half-pontic, and beam. Three-dimensional models of the tooth components and CA were created. The target was set at a 0.25-mm distal canine movement. Long-term tooth movement was simulated using an iterative calculation method.

Results: All the groups initially showed crown displacement, distal tipping, and distal rotation. Over time, the movement patterns differed in relation to the design. The no-pontic design exhibited the greatest displacement and tipping. The beam design exhibited the largest initial displacement but showed the lowest displacement and tipping thereafter. Full- and half-pontic designs yielded intermediate results. Significant force reduction was observed immediately after CA application, and was followed by a gradual decrease. The mean tooth-movement achievement rate was approximately 76.7%.

Conclusions: The edentulous space design of the CA substantially affected tooth-movement behavior. An iterative simulation is necessary to evaluate long-term tooth-movement patterns. The beam design demonstrated optimal suitability for bodily movement with minimal tipping. For optimal results, additional setup or overcorrection may be necessary.

Objective: To assess the success rate and proximity of miniscrews to the root using surgical guides produced by integrating data obtained from cone-beam computed tomography and intraoral scanned models.

Methods: This retrospective study involved 113 patients (224 miniscrews) who underwent miniscrew placement as part of their orthodontic treatment. Two operators placed miniscrews between the buccal alveolar bone of each patient and assessed initial stability by measuring the Periotest value (PTV) and insertion torque (IT). Patients were divided into two groups based on the miniscrew insertion method: manual group (MG) and surgical guide group (SG). Root proximity was assessed using periapical radiography, and miniscrews that remained in place for over 6 months were considered successful.

Results: There was a statistically significant difference in the Kaplan-Meier survival curves between the groups (P < 0.05). The success rates of the miniscrews were 79.1% and 90.5% for the MG and SG, respectively (P < 0.05). The root contact rate also differed significantly between the groups (MG, 17.5%; SG, 0.1%; P < 0.001). However, the PTV and IT did not show significant differences between the groups.

Conclusions: Proximity to the root and utilization of surgical guides have the most direct impact on the success rate of miniscrews. Root proximity can be effectively reduced using surgical guides. Therefore, the use of a miniscrew surgical guide is recommended to increase the success rate of miniscrews as stable anchorage devices, particularly in cases with narrow interradicular space.

Objective: Temporary anchorage devices (TADs) have considerably reduced the need for anterior segmental osteotomy (ASO) in patients with Class I malocclusion. Most previous studies have been published before the widespread use of TADs, thus warranting new guidelines for determining the optimal approach for surgery and orthodontic treatment. This study aimed to establish guidelines on the choice between ASO and non-ASO (NASO) based on soft tissue considerations.

Methods: Sixty-seven patients diagnosed with skeletal Class II malocclusion were divided into the ASO (n = 31) and NASO (n = 36) groups. Cephalometric analyses were used to compare the initial and final records to assess the effect of treatment on soft tissues. The interlabial gap, upper lip anterior to the E-line, lower lip anterior to the E-line, H-angle, upper lip to the nasion-perpendicular line, and nasolabial angle were evaluated. In particular, a proportional difference indicator between the upper and lower lips relative to the pogonion angle between the facial plane and CK line was presented, followed by statistics analyses. Statistical significance was set at P < 0.05.

Results: Both groups demonstrated normal proportions of the upper and lower lips; however, significant differences favoring ASO over NASO in terms of soft tissue changes were observed for several variables.

Conclusions: ASO is advised if the required adjustment for the upper and lower lips is -4.0 mm and -5.0 mm, respectively. For modifications of -2.0 mm, NASO is preferred. This study provides clinical guidelines on the choice between ASO and NASO based on the required lip movement measurements.

Objective: To evaluate the effects of rapid maxillary expansion (RME) on nasal patency and nasomaxillary dimensions in children and adolescents with mouthbreathing through 8 years of clinical follow-up.

Methods: RME was performed using a Hyrax orthodontic appliance in 28 mouth-breathers (6-13 years old). During follow-up, objective tests of nasal respiratory function were conducted, such as acoustic rhinometry, which provided the minimum cross-sectional areas of the nasal cavity, and active anterior computed rhinomanometry, which measured inspiratory nasal resistance. The tomographic widths of the coronal sections of the nose and maxilla were also measured. Fisher's exact test and the Mann-Whitney U test were used to compare categorical and numerical variables, respectively, in mouth-breathers with and without allergic rhinitis. Temporal evolution was assessed using generalized estimating equation models. Statistical significance was set at P < 0.05.

Results: There was a reduction in inspiratory resistance after RME with a stable improvement in nasal patency during the 8-year follow-up period (P = 0.0179). All nasal and maxillary tomographic widths showed statistically significant increases in the short-term (P < 0.0001), and most of them showed significant increases in the long-term when compared with the pre-expansion period. Tomographic measurements were not influenced by allergic rhinitis.

Conclusions: Our study showed that RME promoted and maintained the widening of the posterior maxillary structure in children and adolescents with mouth-breathing, with a decrease in inspiratory nasal resistance during the 8-year follow-up period. These findings highlight the importance of RME in mouth-breathers with maxillary atresia.

Objective: Orthodontic appliances are commonly used to achieve anchorage during orthodontic treatments; however, their use can contribute to oral diseases. Studies have shown that bisphosphonates and osteoprotegerin are highly effective in reducing orthodontic tooth movement. To determine the efficacy of bisphosphonates and osteoprotegerin in reducing orthodontic tooth movement.

Methods: A comprehensive search was conducted across five databases-MEDLINE-PubMed, Scopus, Google Scholar, ScienceDirect, and Taylor & Francis-up to August 2, 2023. Clinical trials conducted in healthy animals, where bisphosphonates and osteoprotegerin were administered during tooth movement, were included. The search identified 3,099 articles, which underwent a two-phase screening process, resulting in twelve studies for the systematic review and seven for the meta-analysis. Risk of bias was assessed using the SYRCLE tool, and Egger's regression was used to evaluate publication bias.

Results: The administration of bisphosphonates was more effective than osteoprotegerin in reducing mesiodistal orthodontic movement. However, osteoprotegerin did not significantly reduce orthodontic tooth movement.

Conclusions: The findings align with previous studies, confirming the superior efficacy of bisphosphonates over osteoprotegerin. Further research is required to determine the optimal dosage and mechanism of action for these drugs in clinical practice, considering the specific objectives of orthodontic treatments.

Objective: This prospective study evaluated the effectiveness of clear aligner treatment (CAT) in achieving dentoalveolar upper arch expansion in patients with mixed dentition and transverse maxillary deficiency.

Methods: Forty patients with mixed dentition and a transverse discrepancy of ≤ 5 mm were treated using clear aligners. Pre- and post-treatment digital dental models were measured using specific landmarks and compared with the programmed expansion in the virtual treatment plan. Statistical analyses included the inter-class correlation coefficient to evaluate inter-rater reliability. A paired t test was employed to compare pre- and post-treatment values and to examine the significance of the changes. Multiple regression analysis was conducted to estimate the relationship between the prescribed and observed measurements, stratified by inter-dental measurements (deciduous canines, first deciduous molars, and permanent molars, at cusp and gingival levels).

Results: Excellent measurement reproducibility was observed. The accuracy of dentoalveolar maxillary arch expansion varied among different tooth regions. The inter-canine accuracy was 87.7% at the cusp level and 82.7% at the gingival level. The inter-first deciduous molars exhibited accuracies of 84.9% (cusp level) and 80.5% (gingival level). The inter-first molars showed accuracies of 77.8% (cusp level) and 67.9% (gingival level). Significant differences were observed between the planned and obtained measurements for specific tooth regions.

Conclusions: CAT demonstrated reliable predictability in achieving dentoalveolar expansion of the maxillary arch in patients with mixed dentition. A higher accuracy was observed in the anterior region than in the posterior region. These findings suggest that CAT could be an effective option for treating transverse maxillary deficiencies in patients with mixed dentition with moderate inter-arch transverse discrepancies, considering tooth-specific predictability differences.

Objective: Extraction of the mandibular second molar (L7) and substitution by the mandibular third molar (L8) is an effective treatment option. This study aimed to evaluate spontaneously erupted L8 occlusion after L7 extraction, and identify the influencing factors.

Methods: This study assessed 46 L8 from 28 patients using dental study models, panoramic radiographs, and lateral cephalograms obtained during L7 extraction (T1) and completion of L8 eruption (T2). At T2, samples were categorized as acceptable (A-group) or unacceptable (U-group) based on the American Board of Orthodontics index. L8 angulation and position, retromolar space, distance between the Xi point and mandibular first molar (L6), and Nolla stage were compared between the groups to identify the predictive factors for successful eruption.

Results: At T2, 58.7% of L8 exhibited acceptable occlusion. Age at T1 was significantly higher in the U-group than that in the A-group. Angles ∟6-MnP and ∟8-MnP differed significantly between the groups at T2. Xi-L6 distance was considerably longer in the A-group than that in the U-group at T1 and T2. Younger age at extraction and Xi-L6 distance at T1 affected the acceptable occlusion.

Conclusions: Younger age at L7 extraction and adequate eruption space (Xi-L6 distance) appear to be the key factors for achieving acceptable L8 occlusion.

Objective: The treatment of asymmetric maxillary hypoplasia and dental crowding secondary to unilateral cleft lip and palate (UCLP) is often challenging. This study introduced an asymmetric tooth-borne distractor in anterior maxillary segmental distraction osteogenesis and used three-dimensional finite element analysis to evaluate its potential for clinical application in cases of asymmetrical maxillary hypoplasia.

Methods: A cone-beam computed tomography scan of a late adolescent with UCLP was used to construct a three-dimensional finite element model of the teeth and maxillary structures. An asymmetric distractor model was used to simulate conventional distraction osteogenesis and asymmetric distraction osteogenesis (ADO) to evaluate the resultant stress distribution and displacement.

Results: Postoperatively, both distraction methods resulted in anterior maxillary segment advancement with a slight upward movement. ADO yielded a greater increase in the dental arch length on the cleft side and induced rotation of the anterior maxillary segment, potentially improving midline deviation. Both methods showed similar stress distributions, with higher stress concentrations on the cleft side.

Conclusions: ADO may offer clinical advantages in correcting asymmetrical maxillary hypoplasia in patients with UCLP by facilitating asymmetrical expansion and rotation of the maxilla. Further research is needed to generalize these findings to other clinical presentations.